1. Field of the Invention
The present invention relates to a system and method of driving shutter, and more particularly to a system and method of driving shutter by tendency of moving object.
2. Description of the Related Art
Nowadays, automatic photographing function is gradually added to the digital cameras because of the computing capability of digital cameras increasing. For example, some cameras can transmit the position of a human face to a cradle head capable of automatically moving by detecting the position of the human face and utilize mutual feedback between two devices to place a main body on the screen. When the position of the human face satisfies specific conditions, the camera would automatically take pictures.
Since the camera has the design of automatically driving a shutter through face detection, many variations and applications about the concept have been recently provided. For example, the design of smile shutter has been added to many cameras in the market such that while a user take a human image with a camera, the shooting time can be decided by the camera according to the facial expression of the main body. There are many similar applications, such as a pet-mode, a blinking detection or a facial recognition, which drive the shutter when the smile expression of main body is detected. These designs of automatically driving the shutter are usually concentrated on applications of faces or known main-bodies or behavior. In practice, these designs perform comparison with the main bodies in the database, and automatically drive the shutter after the comparison is successful. However, the foregoing applications are applied at static main bodies and cannot be applied at a moving object.
While taking pictures, we usually retain instantaneous movement except the static main bodies. These dynamic objects are not limited to subject matters (e.g. faces, pets or facial expressions) that cab be recognized by the camera. For example, a human body moves in a U-shaped pool through a skateboard in extreme sports and performs various movements at the highest point. In this case, the camera will fail to automatically shot the movements performed by the main bodies at the highest point if merely detecting human faces or facial expressions.
Currently, dynamic pictures are difficult to be taken. Generally speaking, the user has to manually operate shutter when shooting a moving object. However, the user usually needs a reaction time before pressing the shutter. Thus, the user presses the shutter when seeing a desired scene, the most wonderful moment has been missed. Since the development of complementary metal-oxide-semiconductor (CMOS) advances and CMOS is characteristic of reducing noise and high sample rate, the difficulty of shooting moving objects are gradually decreasing. Taking the present technology as an example, a high speed CMOS can usually achieve the solution of over ten million pixels to sample at a rate of several sheets or dozens of sheets per second in order to capture every moment of a moving object. However, the solution may cost high price. There are two possible solutions which can be used to shot ten pictures of ten million pixels per second:
(1) The first one is raising the speed of the design of image processing hardware. In this way, hardware requirements will be increased significantly, and the design is aimed at performing optimization on this mode. Its logic requirements may be more than ten times the normal logic requirement under the common shooting mode and additional cost will increase. The solution is infeasible.
(2) The second one is storing unprocessed captured images by an external memory and retrieving the unprocessed captured images from the external memory through post processing after image capturing. However, this manner may need numerous memory spaces. As far as the unprocessed images are considered, they may cost storing space of 100 mega byte per second. The cost expenditure is lower than the foregoing. (1). However, it also needs to pay additional cost at the external memory.
In addition, it may utilize present face detection mechanism as a basis of driving a shutter to shot the moment of a human face turning. However, the foregoing manner may have two problems to cause the difficulty in unsuccessfully taking the desired pictures: firstly, since face detection belongs to the calculation of object matching, the calculation process may not be completed in a moment. Therefore, after face detection, the moved main object usually does not keep the same posture. Secondly, when a human face moves or turns, the moving blur or objects covering may take place (e.g. when faces move, hair may cover portion of faces). Consequently, face detection may not be successfully carried out.